Apparatus for separating metallic fumes from furnace-gases



(No Model.)

. M. W. ILES. APPARATUS FOR SE PARATING METALLIC FUMES FROM FURNACEGASES.

No. 515,084. Patented Feb. 20, 1894.

Win/see E6 MALVERN W. ILES, OF DENVER, COLORADO.

APPARATUS FOR SEPARATING METALLIC FUMES FROM FURNACE-GASES.-

SPEGIFIGATION forming part of Letters ?atent No. 515,084, dated February20, 1894.

Applicationfiled May 31.1893.

T 0 all whom it may concern:

Be it known that I, MALVERN W. has, a citizen of the United States,residing at Denver,in the county of Arapahoe, int-he State of Colorado,have invented a new and Improved Method of and Apparatus for SeparatinMetallic Fumes from Furnace-Gases, of which the following is a true andexact description, reference being had to the accompanying drawing,which forms a part thereof.

My invention relates to the separation and saving of metallic fumesdriven off from metallurgical furnaces and more especially to the savingof the metallic fume driven off from sulphide ores under varioustreatments, particularly in what are known as roasting processes.

The metallic fume driven off from smelting and other kinds of furnaceshave heretofore been saved with great success by passing the mixture ofgases and solid particles constituting the smoke of the furnace througha system of cooling tubes and finally through a screening apparatus,generally made up of a large number of fabric bags in which the solidparticles are arrested while the gases are permitted to escape throughthe fabric. It has been found impracticable however, to so separate fumemixed with a large proportion of sulphuric anhydride and sulphuric acidas these powerful acids would rapidly attack and destroy the screens.

Now the object of my invention is to enable the furnace smoke containinga large proportion of such acids to be successfully screened, and alsoto so change the character of the acid that it will be less dangerousand mischievous. I have discovered that by mixing the gaseous and solidmatter making up the smoke of the furnace in a considerable volume offinely divided heated carbon in the form of smoke and keeping themixture at a proper temperature, the sulphuric anhydride and sulphuricacid will be reduced by the carbon to sulphurous oxide or sulphurous gasand that the resulting mixture of gases and solid matter can be screenedto separate the metallic fume without destruction of the screens.

The chemical reaction which takes place may be expressed as follows: SOplus heated fine carbon equals SO plus 00 or at a higher Serial No.476,070. (No model.)

temperature, the action would probably be as follows:

My new method and the character of apparatus advisable for carrying itinto effect will be best understood as described in connection with thedrawing which illustrates in a diagrammatic form an apparatus suitablefor my purpose and in which A indicates a reverberatory furnace such asis commonly used for roasting sulphide ores, A indicating the hearthupon which the ores are placed; B the fire place of the furnace, and Cthe grate thereof, while D indicates the opening at the end of thefurnace through which the furnace smoke is discharged.

E and E indicate a smoke chamber or flue connected directly with thepassage D and preferably formed with non-conducting walls of refractorymaterial, at least as to that part of it in immediate connection withthe furnace; I prefer also to make that part of' the smoke chamber inimmediate connection with the furnace in the form of a vertical tower asindicated at E.

F indicates a system of cooling fiues connected with the smoke chamber EE and which should be of sufficient extent to insure the cooling down ofthe smoke to a point where its heat will not injuriously affect thematerial of the screens.-

G indicates a fan, the function of which is to draw the smoke throughthe cooling fiues and deliver it into a conduit H, which, as shown, is ahopper box, to the top of which are connected a series of fabric bagsindicated at I. The gaseous portion of the smoke can escape freelythrough the bags while the solid particles are retained within the sameand fall down into the hopper H from which they are withdrawn atconvenient intervals.

J indicates a supplementary or auxiliary furnace which may be of anykind ordescription and the function of which is to produce a largevolume of carbonaceous smoke and deliver the same into the smoke chamberinto which the gases, &c., driven off from the roastin g furnace arealso delivered. The carbonaceous smoke can be formed from bituminouscoal, hydro-carbon oils, or any other materials which may be convenientand which can be made to yield a large quantity of finely divided carbonin the form of smoke. The position of the smoke producing furnace J andthe point at which its flue K delivers its smoke into the smoke conduitof the roasting furnace is not important so long as the carbon smoke ismixed with the roaster smoke at a point where the temperature of themixture can be maintained or raised to a proper degree of heat to insurethe reducing action of the carbon upon the sulphuric acid. (I use theterm sulphuric acid as covering both the sulphuric acid and sulphuricanhydride and intend to be so understood Where the expression is used inthe claims.) I have shown the smoke flue K as opening into the lowerportion of the vertical part E of the smoke box but it can convenientlybe made to open into the furnace A at or near the passage E, forinstance, at a point indicated at K in the drawing.

My reason for preferring to construct that portion of the smoke fiue inimmediate connection with the furnace Awith non-conducting walls, is toprevent the escape of heat, and insure a high temperature beingmaintained in the mixed smoke for a sufficient length of time to insurethe reaction between the finely divided carbon and sulphuric acid andfor the same reason and also to insure a thorough mixture of the roastersmoke and the carbonaceous smoke I find it advisable to form thatportion of the flue, for a portion of its length at least, as a verticaltower. The reaction between the sulphuric acid and carbon beingcompleted or at least sufficient to deprive the furnace smoke of itsdestructive character, the mixed smoke is next cooled by passing throughthe fines F and is then forced through the screen system to separate thesolid and gaseous constituents.

Besides the advantage of saving the metallic fume which would otherwisebe lost, my method has the additional advantage of producing instead ofsulphuric acid, sulphurous acid, which is both less destructive andlighter than the sulphuric acid and which consequently is more easilydissipated in the atmosphere and less likely to injure workmen andvegetation in the neighborhood of the screen system.

Having now described my invention, what I claim as new, and desire tosecure by Letters Patent, is-

1. The method of treatin g furnace gases and fumes containing sulphuricacid which consists in mixing the hot gases from the furnace with finelydivided carbon in the form of smoke to effect the reduction of thesulphuric acid to sulphurous acid.

2. The method of saving metallic fumes driven off from furnaces inadmixture with sulphuric acid which consists in mixing the hotfume-bearing furnace gases with finely divided carbon in the form ofsmoke to effect the reduction of the sulphuric acid to sulphurous acid,then cooling the mixed gases, and finally separating the fumes from thegaseous elements of the mixture in screens.

3. The method of saving metallic fumes driven off from furnaces inadmixture with sulphuric-acid which consists in mixing the hot fumebearing furnace gases with finely divided carbon in the form of smoke,and passing the mixture through the heated fines to effect the reductionof the sulphuric acid to sulphurous acid, then cooling the mixed gasesand finally separating the fumes from the gaseous elements of themixture.

4. The described method of saving metallic fumes driven off in thetreatment of sulphide ores which consists in roasting said-sulphide oresto drive off sulphur, mixing thehot gases and fumes driven off byroasting witha large volume of finely divided carbon in the formof'smoke' to reduce the sulphuric acidto sulphurous acid, cooling thegases and finally separating the fume therefrom by screening.

MALVERN W. ILES.

Witnesses:

JOHN M. WALKER, JOHN S. WILLIAMS.

